U.S. patent number 10,788,690 [Application Number 16/257,635] was granted by the patent office on 2020-09-29 for optical isolator array for use in an optical subassembly module.
This patent grant is currently assigned to Applied Optoelectronics, Inc.. The grantee listed for this patent is Applied Optoelectronics, Inc.. Invention is credited to Ziliang Cai, Kai-Sheng Lin, Kevin Liu.
![](/patent/grant/10788690/US10788690-20200929-D00000.png)
![](/patent/grant/10788690/US10788690-20200929-D00001.png)
![](/patent/grant/10788690/US10788690-20200929-D00002.png)
![](/patent/grant/10788690/US10788690-20200929-D00003.png)
![](/patent/grant/10788690/US10788690-20200929-D00004.png)
![](/patent/grant/10788690/US10788690-20200929-D00005.png)
![](/patent/grant/10788690/US10788690-20200929-D00006.png)
United States Patent |
10,788,690 |
Lin , et al. |
September 29, 2020 |
Optical isolator array for use in an optical subassembly module
Abstract
This present disclosure is generally directed to an optical
isolator array with a magnetic base that allows for mounting and
alignment of N number of optical isolators modules within an
optical subassembly module. In an embodiment, the magnetic base
provides at least one mounting surface for coupling to N number of
optical isolators, with N being equal to an optical channel count
for the optical subassembly (e.g., 4-channels, 8-channels, and so
on). The magnetic base includes an overall width that allows for a
desired number of optical isolators to get mounted thereon. Each
optical isolator can be uniformly disposed along the same axis on
the magnetic base and at a distance D from adjacent optical
isolators. An adhesive such as ultraviolet-curing (UV-curing)
optical adhesives may be used to secure each optical isolator at a
predefined position and increase overall structural integrity.
Inventors: |
Lin; Kai-Sheng (Sugar Land,
TX), Liu; Kevin (Houston, TX), Cai; Ziliang
(Richmond, TX) |
Applicant: |
Name |
City |
State |
Country |
Type |
Applied Optoelectronics, Inc. |
Sugar Land |
TX |
US |
|
|
Assignee: |
Applied Optoelectronics, Inc.
(Sugar Land, TX)
|
Family
ID: |
70826704 |
Appl.
No.: |
16/257,635 |
Filed: |
January 25, 2019 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20200241334 A1 |
Jul 30, 2020 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02F
1/093 (20130101); G02B 6/4246 (20130101); G02B
6/4208 (20130101) |
Current International
Class: |
G02F
1/01 (20060101); G02F 1/09 (20060101) |
Field of
Search: |
;359/484.03 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Alexander; William R
Assistant Examiner: Duong; Henry A
Attorney, Agent or Firm: Grossman Tucker Perrault &
Pfleger, PLLC Kinsella; Norman S.
Claims
What is claimed is:
1. An optical isolator array for use in an optical subassembly
module, the optical isolator array comprising: a first magnetic
base defining at least one mounting surface; a plurality of optical
isolators mounted to the at least one mounting surface, each of the
plurality of optical isolators disposed substantially in parallel
relative to each other; and at least one layer of adhesive disposed
on the at least one mounting surface to couple the plurality of
optical isolators to the first magnetic base and to hold each
optical isolator of the plurality of optical isolators at a
predefined position relative to each other.
2. The optical isolator array of claim 1, wherein the magnetic base
is formed from a permanent magnet.
3. The optical isolator array of claim 1, wherein the magnetic base
introduces a first magnetic field that intersects with the
plurality of optical isolators to establish a direction of
propagation.
4. The optical isolator array of claim 1, wherein each optical
isolator of the plurality of optical isolators comprises a Faraday
Isolator.
5. The optical isolator array of claim 1, wherein each optical
isolator of the plurality of optical isolators includes an angled
light-receiving surface to receive channel wavelengths from an
associated laser diode.
6. The optical isolator array of claim 1, wherein the plurality of
optical isolators is disposed uniformly across the at least one
mounting surface.
7. The optical isolator array of claim 1, wherein the at least one
layer of adhesive is disposed between adjacent optical isolators of
the plurality of optical isolators.
8. The optical isolator array of claim 1, wherein the magnetic base
includes a substrate mating surface, and whereby the substrate
mating surface is substantially flat to correspond with a mounting
surface of a substrate and to mount thereto.
9. The optical isolator array of claim 1, further comprising a
second magnetic base, the second magnetic base being coupled to the
plurality of optical isolators via the at least one layer of
adhesive.
10. The optical isolator array of claim 9, wherein the second
magnetic base introduces a second magnetic field, the second
magnetic field intersecting with the plurality of optical
isolators.
11. An optical transceiver, the optical transceiver comprising: a
transceiver housing; at least one optical transmitter subassembly
(TOSA) arrangement disposed in the transceiver housing, the at
least one TOSA arrangement comprising: a substrate defined by at
least one mounting surface; a plurality of laser diodes mounted to
the at least one mounting surface of the substrate, each laser
diode of the plurality of laser diodes to emit a different
associated channel wavelength along a corresponding light path of a
plurality of light paths; and an optical isolator array mounted to
the at least one mounting surface adjacent the plurality of laser
diodes such that the plurality of light paths intersect with the
optical isolator array, the optical isolator array comprising a at
least a first magnetic base and a plurality of optical isolators
coupled thereto, and wherein each optical isolator is optically
aligned with a corresponding laser diode of the plurality of laser
diodes via a corresponding light path; an optical receiver
subassembly (ROSA) disposed in the transceiver housing.
12. The optical transceiver of claim 11, wherein the first magnetic
base of the optical isolator array is formed from a permanent
magnet.
13. The optical transceiver of claim 11, wherein the first magnetic
base introduces a first magnetic field that intersects with the
plurality of optical isolators to establish a direction of
propagation.
14. The optical transceiver of claim 11, wherein each optical
isolator of the plurality of optical isolators includes an angled
light-receiving surface to receive channel wavelengths from a
corresponding laser diode of the plurality of laser diodes.
15. The optical transceiver of claim 11, wherein the plurality of
optical isolators is disposed uniformly across the at least one
mounting surface.
16. The optical transceiver of claim 11, wherein at least one layer
of adhesive is disposed between adjacent optical isolators of the
plurality of optical isolators.
17. The optical transceiver of claim 11, wherein the first magnetic
base includes a substrate mating surface, and whereby the substrate
mating surface is substantially flat to correspond with the
mounting surface of a substrate to mount thereto.
18. The optical transceiver of claim 11, further comprising a
second magnetic base, the second magnetic base being coupled to the
plurality of optical isolators and the first magnetic base via at
least one layer of adhesive.
19. The optical transceiver of claim 18, wherein the second
magnetic base introduces a second magnetic field, the second
magnetic field intersecting with the plurality of optical
isolators.
Description
TECHNICAL FIELD
The present disclosure relates to optical communications, and more
particularly, to an optical isolator array for use in a
multi-channel optical subassembly module, the optical isolator
array having a magnetic base with a relatively compact and modular
profile that supports N number of optical isolators for use in an
optical subassembly module.
BACKGROUND INFORMATION
Optical transceivers are used to transmit and receive optical
signals for various applications including, without limitation,
internet data center, cable TV broadband, and fiber to the home
(FTTH) applications. Optical transceivers provide higher speeds and
bandwidth over longer distances, for example, as compared to
transmission over copper cables. The desire to provide higher
transmit/receive speeds in increasingly space-constrained optical
transceiver modules has presented significant challenges. Moreover,
optical transceiver modules include a wide-range of package
profiles with large variations in channel density and housing
dimensions, for instance, that can make reusability of components
difficult across multiple types of profiles, if not impossible.
For example, some approaches to transmitter optical subassemblies
(TOSAs) include having a plurality of laser arrangements including,
for example, a laser diode driver (LDD), laser diode, focus lens
and multiplexer device, and a multiplexing device for combining
channel wavelengths from each of the plurality of laser
arrangements in a single housing. Each component of the TOSA must
be securely attached and optically aligned with other associated
optical components, which presents significant challenges for part
designs (e.g., sub-mounts, lenses, mirror holders, and so on) that
can be reused between package types, particularly as TOSAs continue
to scale. In addition, manufacture of such TOSAs routinely require
multiple test, correction, and re-test stages, which can ultimately
increase per-unit manufacture time, complexity, and reduce
yield.
BRIEF DESCRIPTION OF THE DRAWINGS
These and other features and advantages will be better understood
by reading the following detailed description, taken together with
the drawings wherein:
FIG. 1 shows a block diagram of a multi-channel optical transceiver
in accordance with an embodiment of the present disclosure.
FIG. 2 shows a perspective view of an optical isolator array for
use in the optical transceiver of FIG. 1, in accordance with an
embodiment of the present disclosure.
FIG. 3 shows a front view of the optical isolator array of FIG. 2,
in accordance with an embodiment of the present disclosure.
FIG. 4 shows a side view of the optical isolator array of FIG. 2,
in accordance with an embodiment of the present disclosure.
FIG. 5 shows a perspective view of the optical isolator array of
FIG. 2 coupled to an optical subassembly substrate, in accordance
with an embodiment of the present disclosure.
FIG. 6 shows a top-down view of the optical isolator array of FIG.
2 and associated optical components, in accordance with an
embodiment of the present disclosure.
FIG. 7 shows another example optical isolator array suitable for
use in the optical transceiver of FIG. 1, in accordance with an
embodiment of the present disclosure.
FIG. 8 shows a side view of the example optical isolator array of
FIG. 7, in accordance with an embodiment of the present
disclosure.
DETAILED DESCRIPTION
This present disclosure is generally directed to an optical
isolator array with a magnetic base (or plate) that allows for
mounting and alignment of N number of optical isolator chips,
referred to herein as simply optical isolators, within an optical
subassembly module. In an embodiment, the magnetic base provides at
least one mounting surface for supporting and coupling to N number
of optical isolators, with N being equal to an optical channel
count for the optical subassembly (e.g., 4-channels, 8-channels,
and so on). The magnetic base includes an overall width that allows
for a desired number of optical isolators to get mounted thereon.
Each optical isolator can be disposed along the same axis on the
magnetic base and at a uniform distance from adjacent optical
isolators. The optical isolators can extend substantially parallel
relative to each other when coupled to the magnetic base. Further,
each optical isolator provides a light-receiving surface at a first
end to receive channel wavelengths from a corresponding laser
diode, and a light-emitting surface at a second end, opposite the
first end, to pass the received channel wavelengths along a
direction of propagation. The polarity and orientation of the
magnetic base within the optical subassembly module establishes the
direction of propagation through each optical isolator. The
magnetic base introduces a magnetic field with a magnetic field
strength sufficient to ensure nominal power along the desired
direction of propagation. Accordingly, each optical isolator
coupled to the magnetic base can pass channel wavelengths along the
same direction. In an embodiment, this includes optical isolators
passing channel wavelengths along a corresponding light path that
extends parallel relative to each other. An adhesive such as
ultraviolet-curing (UV-curing) optical adhesives may be used to
secure each optical isolator at a predefined position on the
magnetic base and provide additional structural support. Other
types of adhesives and fixation approaches may be utilized and are
within the scope of this disclosure.
In another embodiment of the present disclosure, an optical
isolator array is disclosed that includes first and second magnetic
bases or plates disposed opposite each other and a plurality of
optical isolators sandwiched/disposed therebetween. The optical
isolators may be coupled via, for instance, adhesive or other
suitable approach to the first and second magnetic bases. The first
and second magnetic bases introduce a first and second magnetic
field, respectively, and can determine a direction of propagation
for the optical isolators based on the same. The magnetic field
strength of the first and second magnetic bases may be
substantially equal, or different depending on a desired
configuration. The addition of a second magnet, and by extension, a
second magnetic field, results in greater isolation performance
relative to that of a single magnetic field.
Continuing on, each of the first and second magnetic bases may be
configured identically, and thus, either magnetic base can be
utilized to couple the optical isolator array to the surface of a
substrate, e.g., the sidewall of a transmitter optical subassembly
(TOSA). In this embodiment, at least one layer of adhesive may
extend between the first and second magnetic bases to securely hold
the optical isolators in a predetermined position between the first
and second magnetic bases and can increase the overall structural
integrity of the optical isolator array.
Numerous advantages will be apparent over other approaches that
utilize discrete/separate optical isolators coupled to a substrate.
For example, an optical isolator array consistent with the present
disclosure can be easily be shortened or lengthened to accommodate
different optical subassembly housing/packaging requirements and/or
when less or more optical channels are desired. The total number of
optical isolators may vary according to desired channel counts, and
such modifications are achievable without substantial redesign of
the optical isolator array. Alternatively, or in addition, the
distance/pitch between adjacent optical isolator chips may be
varied to accommodate a wide-range of package designs.
In addition, an optical isolator array consistent with the present
disclosure may be separately manufactured and optionally tested
apart from other optical subassembly components, and then
subsequently coupled into an associated housing, e.g., a TOSA
housing, as a single unit. This advantageously ensures that each of
the optical isolators are optically aligned with associated active
and/or passive optical components, e.g., multiplexers, laser
diodes, and so on, by virtue of the optical isolator array being
coupled to the optical subassembly at a predefined position. The
orientation of each optical isolator can be uniformly adjusted in
tandem at a fine-grain level (e.g., by less than 10 microns) by
simply shifting the physical position of the magnetic base relative
to associated optical components, thus minimizing or otherwise
reducing the overall number adjustments to achieve nominal power.
This can significantly reduce manufacturing complexity, error, and
the number of fix-and-repeat testing iterations that normally
characterizes optical subassembly manufacturing.
While the present disclosure includes examples and scenarios
directed specifically to optical isolator arrays being used in a
transmitter optical subassembly (TOSA) arrangement, this disclosure
is not limited in this regard. For example, an optical isolator
consistent with the present disclosure may be utilized to align and
mount optical isolators in receiver optical subassembly (ROSA)
arrangements.
As used herein, "channel wavelengths" refer to the wavelengths
associated with optical channels and may include a specified
wavelength band around a center wavelength. In one example, the
channel wavelengths may be defined by an International
Telecommunication (ITU) standard such as the ITU-T dense wavelength
division multiplexing (DWDM) grid. This disclosure is equally
applicable to coarse wavelength division multiplexing (CWDM). In
one specific example embodiment, the channel wavelengths are
implemented in accordance with local area network (LAN) wavelength
division multiplexing (WDM), which may also be referred to as
LWDM.
The term "coupled" as used herein refers to any connection,
coupling, link or the like and "optically coupled" refers to
coupling such that light from one element is imparted to another
element. Such "coupled" devices are not necessarily directly
connected to one another and may be separated by intermediate
components or devices that may manipulate or modify such signals.
On the other hand, the term "direct optical coupling" refers to an
optical coupling via an optical path between two elements that does
not include such intermediate components or devices, e.g., a
mirror, waveguide, and so on, or bends/turns along the optical path
between two elements.
The term substantially, as generally referred to herein, refers to
a degree of precision within acceptable tolerance that accounts for
and reflects minor real-world variation due to material
composition, material defects, and/or limitations/peculiarities in
manufacturing processes. Such variation may therefore be said to
achieve largely, but not necessarily wholly, the stated/nominal
characteristic. To provide one non-limiting numerical example to
quantify "substantially," such a modifier is intended to include
minor variation that can cause a deviation of up to and including
.+-.5% from a particular stated quality/characteristic unless
otherwise provided by the present disclosure.
Referring to the Figures, FIG. 1, an optical transceiver 100,
consistent with embodiments of the present disclosure, is shown and
described. In this embodiment, the optical transceiver 100 includes
a multi-channel transmitter optical subassembly (TOSA) arrangement
104 and a multi-channel receiver optical subassembly (ROSA)
arrangement 106 coupled to a substrate 102, which may also be
referred to as an optical module substrate. The substrate 102 may
comprise, for example, a printed circuit board (PCB) or PCB
assembly (PCBA). The substrate 102 may be configured to be
"pluggable" for insertion into an optical transceiver cage 109.
In the embodiment shown, the optical transceiver 100 transmits and
receives four (4) channels using four different channel wavelengths
(.lamda.1, .lamda.2, .lamda.3, .lamda.4) via the multi-channel TOSA
arrangement 104 and the multi-channel ROSA arrangement 106,
respectively, and may be capable of transmission rates of at least
about 25 Gbps per channel. In one example, the channel wavelengths
.lamda.1, .lamda.2, .lamda.3, .lamda.4 may be 1270 nm, 1290 nm,
1310 nm, and 1330 nm, respectively. Other channel wavelengths are
within the scope of this disclosure including those associated with
local area network (LAN) wavelength division multiplexing (WDM).
The optical transceiver 100 may also be capable of transmission
distances of 2 km to at least about 10 km. The optical transceiver
100 may be used, for example, in Internet data center applications
or fiber to the home (FTTH) applications. Although the following
examples and embodiments show and describe a 4-channel optical
transceiver, this disclosure is not limited in this regard. For
example, the present disclosure is equally applicable to 2, 6, or
8-channel configurations.
In more detail, the multi-channel TOSA arrangement 104 includes a
TOSA housing 114 with a plurality of sidewalls that define a cavity
(not shown). The cavity includes a plurality of laser arrangements
110, an optical isolator array 127, and a multiplexing device 124
disposed therein. The optical isolator array 127 may be implemented
as the optical isolator array 200 of FIGS. 2-6 or the optical
isolator array 200' of FIGS. 7-8, which will be discussed in
greater detail below. In an any event, each laser arrangement of
the plurality of laser arrangements 110 can be configured to
transmit optical signals having different associated channel
wavelengths. Each laser arrangement may include passive and/or
active optical components such as a laser diode (LD), monitor
photodiode (MPD), laser diode driver (LDD), and so on. Additional
components comprising each laser arrangement include filters,
optical isolators, filtering capacitors, and so on.
To drive the plurality of laser arrangements 110, the optical
transceiver 100 includes a transmit connecting circuit 112 to
provide electrical connections to the plurality of laser
arrangements 110 within the housing 114. The transmit connecting
circuit 112 may be configured to receive driving signals (e.g.,
TX_D1 to TX_D4) from, for example, circuitry within the optical
transceiver cage 109. The housing 114 may be optionally
hermetically sealed to prevent ingress of foreign material, e.g.,
dust and debris. Therefore, a plurality of transit (TX) traces 117
(or electrically conductive paths) may be patterned on at least one
surface of the substrate 102 and are electrically coupled with a
feedthrough device 116 of the TOSA housing 114 to bring the
transmit connecting circuit 112 into electrical communication with
the plurality of laser arrangements 110, and thus, electrically
interconnect the transmit connecting circuit 112 with the
multi-channel TOSA arrangement 104. The feedthrough device 116 may
comprise, for instance, ceramic, metal, or any other suitable
material.
In operation, the multi-channel TOSA arrangement 104 may then
receive driving signals (e.g., TX_D1 to TX_D4), and in response
thereto, generates and launches multiplexed channel wavelengths on
to an output waveguide 120 such as a transmit optical fiber. The
generated multiplexed channel wavelengths may be combined based on
a demultiplexing device 124 such as an arrayed waveguide grating
(AWG) that is configured to receive emitted channel wavelengths 126
from the plurality of laser assemblies 110 and output a signal
carrying the multiplexed channel wavelengths on to the output
waveguide 120 by way of optical fiber receptacle 122.
Continuing on, the multi-channel ROSA arrangement 106 includes a
demultiplexing device 124, e.g., an arrayed waveguide grating
(AWG), a photodiode (PD) array 128, and an amplification circuitry
130, e.g., a transimpedance amplifier (TIA). An input port of the
demultiplexing device 124 may be optically coupled with a receive
waveguide 134, e.g., an optical fiber, by way of an optical fiber
receptacle 136. An output port of the demultiplexing device 124 may
be configured to output separated channel wavelengths on to the PD
array 128. The PD array 128 may then output proportional electrical
signals to the TIA 130, which then may be amplified and otherwise
conditioned. The PD array 128 and the transimpedance amplifier 130
detect and convert optical signals received from the fiber array
133 into electrical data signals (RX_D1 to RX_D4) that are output
via the receive connecting circuit 132. In operation, the PD array
128 may then output electrical signals carrying a representation of
the received channel wavelengths to a receive connecting circuit
132 by way of conductive traces 119 (which may be referred to as
conductive paths).
Referring to FIGS. 2-6, an example optical isolator array 200 is
shown consistent with an embodiment of the present disclosure. As
shown, the optical isolator array 200 includes a magnetic base 202
(or magnetic plate) and a plurality of optical isolators shown
collectively as 204 and individually as 204-1 to 204-4. The
magnetic base 202 may be formed from a metal or metal alloy such as
iron, nickel, cobalt, or any combination thereof. In an embodiment
the magnetic base 202 may be configured as a permanent magnet
device, although other types of magnets are within the scope of
this disclosure as such electromagnet devices.
A plurality of sidewalls define the magnetic base 202 and provide
at least a first mounting surface 207. The first mounting surface
207 can be substantially planar, as shown, although in other
embodiments the first mounting surface 207 may not necessarily be
flat. The first mounting surface 207 supports the plurality of
optical isolators 204. The overall width W1 (See FIG. 3) of the
magnetic base 202 may be a function of the desired number of
optical isolators. For instance, in the embodiment shown in FIG. 3
the overall width W1 may measure about 100 microns with each of the
plurality of optical isolators 204 having a corresponding with of
about 20 microns. In this example, 100 microns may be chosen for
the overall width W1 to allow for a portion of the overall width
W1, namely widths W2 and W3, to provide adhesive overflow regions,
with W2 and W3 each measuring equally at about 10 microns. This
advantageously provides sufficient mounting space for the four
optical isolators as well as surface area to allow each end of the
at least one layer of adhesive 206 to flow and cure without
overflowing beyond the sides of the magnetic base 202. Thus, the
following equation may be used to determine the overall width W1 of
the magnetic base 202: W1=N*Wn+Wn Equation (1) with W1 being the
overall length, N being the desired number of optical isolators,
and Wn being the width of an optical isolator.
On the other hand, the overall height H1 of the magnetic base 202
may be chosen to ensure, for instance, that each optical isolator
of the plurality of optical isolators 204 is aligned vertically
with an associated laser arrangement along a Z axis, which will be
discussed in greater detail below with regard to FIG. 7.
Each of the plurality of optical isolators 204 can comprise
polarization-insensitive Faraday Isolators that include multiple
segments/portions including a rotator portion sandwiched/disposed
between first and second polarization sections. The first and
second polarization sections polarizers can comprise birefringent
wedges, e.g. made of rutile (TiO2). This configuration is
particularly well suited for space constrained housing. Each of the
plurality of optical isolators 204 may include segments formed from
different materials to target desired channel wavelengths.
The plurality of optical isolators may be secured at a predefined
position on the first mounting surface 207 via at least one layer
of adhesive 206. As shown, the at least one layer of adhesive 206
may be disposed in a manner that at least partially surrounds each
optical isolator of the plurality of optical isolators 204. The at
least one layer of adhesive 206 may flow during a depositing
process along a direction that is substantially transverse relative
to the first mounting surface 207 based on capillary action caused
by proximity of each of the plurality of optical isolators 204, or
may simply cure as shown based on being disposed between each
optical isolator of the plurality of optical isolators 204. In
either case, the at least one layer of adhesive 206 can be used as,
in a general sense, a submount to hold and/or support each of the
plurality of optical isolators at a predefined position relative to
the magnetic base 202.
To this end, a method for forming the optical isolator array 200
may include first disposing the at least one layer of adhesive 206
on to the mounting surface 207 of the base followed by disposing
each of the plurality of optical isolators 204 at their predefined
positions. Notably, the use of adhesives to hold each optical
isolator 204-1 to 204-4 in place advantageously allows for
relatively simple, fine-grain adjustments to the pitch/distance
between optical isolators. As further shown in FIG. 3, each of the
plurality of optical isolators 204 may be disposed at predefined
positions that include a uniform distance of D1 between adjacent
optical isolators. The at least one layer of adhesive 206 may
vertically displace each of the plurality of optical isolators 204
by a distance D2. Distance D2 may be uniform across the plurality
of optical isolators 204, although variations may be introduced by
design and/or by function of how the at least one layer of adhesive
206 cures. Each of the optical isolators may be further disposed
parallel with each other in a linear array.
With specific reference to FIG. 4, the magnetic base 202 introduces
a first magnetic field 212-1. As shown, the flux lines of the first
magnetic field 212-1 intersect with each of the optical isolators
in the plurality of optical isolators 204 mounted to the magnetic
base 202. In operation, the polarity of the first magnetic field
212-2 therefore determines the direction of propagation for light
which is incident to the plurality of optical isolators 204.
Turning to FIG. 5, the optical isolator array 200 is shown mounted
to a substrate 220. In particular, the magnetic base 202 of the
optical isolator array 200 is coupled to the mounting surface 221
provided by the substrate 220 by way of a substrate mating surface
230. The substrate mating surface 230 may be substantially planar
and correspond with the mounting surface 221 of a substrate
220.
The substrate 220 may comprise, for example, a printed circuit
board (PCB), a sidewall of a housing (e.g., made of metal or other
suitably rigid material) or any other suitable material. The
optical isolator array 200 may be at least partially assembled
separately from other components in an optical subassembly and
later coupled during manufacturing processes as effectively, a
single piece. Accordingly, each of the plurality of optical
isolators 204 may be disposed at a predetermined orientation and
position on the magnetic base 202 to ensure that each will be
aligned within nominal tolerances along and X and Y axis. Optical
alignment of the optical isolator array 200, and more particularly
each of the optical isolators mounted thereon, with associated
passive and/or active optical components, e.g., a laser diode, may
therefore be achieved by simply coupling the optical isolator 200
at a predefined location on the mounting surface 221 of the
substrate 220. The overall height H1 (See FIG. 3) may then displace
the plurality of optical isolators 200 along the Z axis such that
each optical isolator is optically aligned within nominal
tolerances of associated active and/or passive components.
For example, and as shown in the highly simplified embodiment of
FIG. 6, each of the optical isolators 204-1 to 204-4 may be
optically aligned with a corresponding collimating lens of a
plurality of collimating lenses 205 and corresponding laser diode
208-1 to 208-4 of the plurality of laser diodes 208 based at least
in part on the dimensions of the magnetic base 202. This
advantageously allows for the mounting surface 221 of the substrate
220 to act as a stop for the substrate mating surface 230 and
provide a positive indication that each of the optical isolators is
at a desired position along the Z axis simply by having the
substrate mating surface 230 of the magnetic base 202 flush with
the mounting surface 221 of the substrate 220. Likewise, alignment
for each of the plurality of optical isolators 204 along the X and
Y axis requires simply ensuring the magnetic base 202 is positioned
at a predetermined X and Y position relative to the associated
optical components.
Each of the laser diodes 208-1 to 208-4 may be configured to emit a
different channel wavelength. Following the laser diodes 208, each
of the optical isolators 204-1 to 204-4 include a light-receiving
surface (e.g., light-receiving surface 209-1) for receiving channel
wavelengths from a corresponding laser diode of the laser diodes
208-1 to 208-4, and a light-emitting surface (e.g., light-emitting
surface 211-1) disposed opposite the light-receiving surface for
passing the received channel wavelengths to the multiplexing
device, e.g., the multiplexing device 124 (FIG. 1). Each
light-receiving and light-emitting surface may be angled, e.g., at
about 8 degrees, relative to a corresponding light path, such as
shown.
Thus, after coupling of the optical isolator array 200 on the
substrate 220, an optical path may then extend from each an
emission surface of each of the laser diodes 208-1 to 208-4,
through an associated collimating lens of the plurality of
collimating lenses 205 and then through the an associated optical
isolator of the plurality of optical isolators 204. Each of the
light paths may extend substantially parallel to each other,
although other embodiments are within the scope of this
disclosure.
FIG. 7 shows another example optical isolator array 200' in
accordance with an embodiment of the present disclosure. As shown,
the optical isolator array 200' is substantially similar to the
optical isolator array 200 discussed above with regard to FIGS.
2-6, the description of which is equally applicable to the
embodiment of FIG. 7 but will not be repeated for brevity. However,
the example optical isolator array 200' includes a second magnetic
base 203. The second magnetic base 203 may be disposed on an upper
surface of the optical isolators 204-1 to 204-4, or alternatively
supported by the at least one layer of adhesive 206' disposed
between the optical isolators 204 and the second magnetic base
203.
Therefore, the plurality optical isolators 204 and the at least one
layer of adhesive 206' can be sandwiched/disposed between the first
and second magnetic bases 202, 203. The first and second magnetic
bases may extend substantially parallel relative to each other and
may have identical dimensions, although other embodiments are
within the scope of this disclosure. As shown, the at least one
layer of adhesive 206' may extend a distance D2 from the mounting
surface 207 of the first magnetic base 202 up to a mounting surface
213 of the second magnetic base 203. To this end, the at least one
layer of adhesive 206' securely attaches the first and second
magnetic bases 202, 203 to each other, and more importantly,
securely fixes the optical isolators 204-1 to 204-4
therebetween.
As shown in FIG. 8, the first and second magnetic base 202, 203
introduce first and second magnetic fields 212-1, 212-2,
respectively. The first and second magnetic fields 212-1, 212-2 may
at least partially overlap, or not, depending on a desired
configuration. In either case, the polarity of the first and second
magnetic fields 212-1, 212-2 may be utilized to establish a
direction of propagation for wavelengths incident to the plurality
of optical isolators 204.
In accordance with an aspect of the present disclosure an optical
isolator array for use in an optical subassembly module is
disclosed. The optical isolator array comprising a first magnetic
base defining at least one mounting surface, a plurality of optical
isolators mounted to the at least one mounting surface, each of the
plurality of optical isolators disposed substantially in parallel
relative to each other, and at least one layer of adhesive disposed
on the at least one mounting surface to couple the plurality of
optical isolators to the first magnetic base and to hold each
optical isolator of the plurality of optical isolators at a
predefined position relative to each other.
In accordance with another aspect of the present disclosure an
optical transceiver is disclosed. The optical transceiver
comprising a transceiver housing, at least one optical transmitter
subassembly (TOSA) arrangement disposed in the transceiver housing,
the at least one TOSA arrangement comprising a substrate defined by
at least one mounting surface, a plurality of laser diodes mounted
to the at least one mounting surface of the substrate, each laser
diode of the plurality of laser diodes to emit a different
associated channel wavelength along a corresponding light path of a
plurality of light paths, and an optical isolator array mounted to
the at least one mounting surface adjacent the plurality of laser
diodes such that the plurality of light paths intersect with the
optical isolator array, the optical isolator array comprising a at
least a first magnetic base and a plurality of optical isolators
coupled thereto, and wherein each optical isolator is optically
aligned with a corresponding laser diode of the plurality of laser
diodes via a corresponding light path, an optical receiver
subassembly (ROSA) disposed in the transceiver housing.
While the principles of the disclosure have been described herein,
it is to be understood by those skilled in the art that this
description is made only by way of example and not as a limitation
as to the scope of the disclosure. Other embodiments are
contemplated within the scope of the present disclosure in addition
to the exemplary embodiments shown and described herein.
Modifications and substitutions by one of ordinary skill in the art
are considered to be within the scope of the present disclosure,
which is not to be limited except by the following claims.
* * * * *